The invention relates to a method for securing cables in a duct or pipe system for flowing media, such as gas, waste water, rain water or mixed water.
German Gebrauchsmuster DE 297 00 912 has disclosed a fiber-optic cable network which is introduced in an inaccessible duct or pipe system. The fiber-optic cable used for this system is fixed using resilient securing elements, for example, the fiber-optic cable being arranged between the wall and the securing element. Appropriate robots are required for the securing or for the introduction of the securing elements in inaccessible duct or pipe systems, which robots, under remote control, set down the securing elements at appropriate distances and thus fix the introduced fiber-optic cable.
A first object of the invention is to provide a method which enables the laying of a cable or other elongate hollow section in a duct or pipe system in a simple manner. This object is achieved with a method comprising the steps of providing a duct or pipe system with at least two accessible locations, and either tensioning a cable with at least one high-tension-strength element between two accessible locations or tensioning a high-tensile-strength element between the two accessible locations and then attaching the cable to the high-tension-strength element.
Furthermore, the invention is based on a second object, which consists in designing a cable network for a duct or pipe system which can be installed by the method according to the invention. This object is achieved by means of a cable network comprising a duct or pipe system having spaced anchoring points and a cable is either fixed to at least one high-tensile-strength element which is attached by securing the element to the anchoring points at appropriate distances or includes the high-tensile-strength element and is anchored in the system to the spaced anchoring points.
By comparison with the known prior art, the method according to the invention and the cable network according to the invention afford considerable advantages, which are primarily manifested in simple and short mounting, the means required for this purpose likewise being simple and extremely cost-effective. Further advantages may be seen in the fact that in the method according to the invention, the duct or the pipe can hardly be blocked up by the introduced cable since there are no deposit points for contaminants to be found within the duct or pipe. The mounting of a cable by anchoring is generally already known from overhead cable technology, so the aids which are essentially familiar in that technology can also be employed in the context of mounting within a duct or pipe system. As is shown, however, there is a need for intensive considerations to use such a laying system in a duct or pipe system, since only relatively complicated mounting methods have been used to date. Thus, in inaccessible duct or pipe systems, robot vehicles have been necessary to date in order to secure the subsequently inserted cables in such a way that they do not constitute an obstacle. It is advantageous, moreover, that the method according to the invention can be used for any type of ducts or pipes made of metal, stoneware or plastic, since the securing for a high-tensile-strength element is performed in each case at the anchoring points which are each arranged at the access locations of the duct or pipe network. It is also advantageous that during duct repairs, for example, the cables or hollow sections can be removed from the duct with extremely little effort, thereby enabling the repair to be carried out without difficulties. Afterwards, the installation is just as simple as during the original laying.
In the case of the method according to the invention, firstly, the cable or the hollow section is pulled in or pushed in. Afterwards, the anchoring points are secured on the shaft walls or shaft outlets of the duct or pipe system. In the simplest case, according to the invention, a high-tensile-strength element, for example a tension cable known per se, such as a steel cable, is suspended from the anchoring points and correspondingly anchored by means of a turnbuckle. Any desired cable or elongate hollow section can then be attached to such a high-tensile-strength element using suitable securing means, for example using clamps or restraint coils. Since the high-tensile-strength element with the attached cable or hollow section is hung in each case in the upper region of the duct or pipe, it does not interfere with the flow of the flowing media, such as gas, waste water, rain water or mixed water, with the result that no deposits can form. In addition, it is still possible to use robots, without any obstructions, for example in order to inspect the duct system. The possible anchoring length of such a high-tensile-strength element with attached cable or hollow section depends in each case on the duct routing and the permissible anchoring force of the high-tensile-strength element. In addition, the high-tensile-strength element can also be additionally fixed in intermediate shafts with the aid of supporting coils or deflection rollers, thereby enabling longer anchoring lengths.
In the case of this method according to the invention, however, it is also possible to use high-tensile-strength cables in which high-tensile-strength elements are already incorporated in the cable structure, in particular in the cable sheath, or in the hollow section, or are secured at the surface. The laying procedure is even simpler in the case of this variant since the high-tensile-strength element already forms a unit with the cable or hollow section, with the result that only one laying operation is required. At the anchoring points, the high-tensile-strength element is then respectively removed from the cable structure or the hollow section and fixed to the anchoring points for anchoring purposes. Anchoring coils can also be wound onto the respective cable, which coils are then suspended from the respective anchoring point. A turnbuckle is then additionally interposed at the other end of the cable or hollow section, the requisite anchoring ultimately being effected by the turnbuckle.
Depending on the method, it is possible to use any desired types of cables for this kind of laying, such as microcables which comprise a thin tube and optical waveguides loosely introduced therein. It is also possible to use dielectric cables, for example an xe2x80x9call dielectric self supportly cablexe2x80x9d (ADSS) having a rodent-proof sheath or else a so-called TOP cable, which is provided with a glass-fiber-reinforced plastic sheath over the cable core. Further types of cables are specified in connection with the description of the Figures.
The present invention is furthermore based on the object or reducing the sag between two anchoring locations in the case of anchored cables or elongate hollow sections within a duct or pipe system. This object that has been set is achieved with a method of the type explained in the introduction by virtue of the fact that at least one contact-pressure means is inserted in the region between two anchoring points within the duct or pipe system, and that the high-tensile-strength element with an attached cable or a cable with at least one high-tensile-strength element or an elongate hollow section with at least on high-tensile-strength element is subsequently pressed against the inner wall of the duct or pipe system as a result of expansion of the contact-pressure means.
As is already known, high-tensile-strength elements with an attached cable, cables with at least one integrated high-tensile-strength element or an elongate hollow section with a high-tensile-strength element are tensioned between entry shafts in duct or pipe systems. If there are very long anchored lengths or if the course of the duct or pipe system is not straight, an increased sag is possible in the central region, which sag means that problems may possibly occur during the customary cleaning processes or during duct operation. According to the invention, then, an expandable or spreadable contact-pressure means is introduced in the region of the largest sag, where it is finally expanded or spread open. As a result, the introduced high-tensile-strength element with attached cable, the cable with an integrated high-tensile-strength element or a hollow section with a high-tensile-strength element is pressed against the inner wall of the duct or pipe system, so that, by this means, there is no longer any sag. As a result of the long anchored length being divided into two partial regions, the sag established in the partial regions is considerably reduced, with the result that it is not necessary to expect nay disruption in duct operation. The contact-pressure means that is used according to the invention is, for example, a plastic hose which, if required, is reinforced with glass fibers and is generally referred to as a xe2x80x9cpart-linerxe2x80x9d. This plastic hose is preferably coated or impregnated with a curable adhesive, with the result that it can be fixed on the inner wall of the duct or pipe system after being expanded or spread open. Such a part-liner is pushed, for example, onto a rubber sac and, with the aid of a robot, is taken to the intended location, usually the middle of an anchored length. At that point, the sac is inflated with air or a propellant gas, with the result that the part-liner is pressed onto the inner wall, where it already sticks by virtue of the adhesive. Once the part-liner has been pressed onto the inner wall, the sac is moved again and, depending on the type of adhesive, the adhesive is cured with the aid of UV or infrared irradiation or with hot air.
It is also possible to use contact-pressure means in the form of spreadable or expandable rings made of plastic or steel, in particular stainless steel. Such contact-pressure means can be used separately by themselves or else in connection with a hose-like part-liner if, for example, the supporting force of the part-liner is to be reinforced. In such a case, firstly, the contact-pressure means in the form of the ring will be installed by spreading or expansion and then the hose-like part-liner will be mounted over it in the manner already described. Suitable adhesives for the part-liner are the materials which are generally suitable for such applications and must be, in particular, resistant to water and chemicals. Thus, the use of two-component adhesives is also entirely possible.
Other advantages and features of the invention will be readily apparent from the following description of the preferred embodiments, the drawings and claims.